blackberry curve 8520 - won't restart

I had to take the battery out of my blackberry. After replacing it and it begins to load, the white bar reaches a certain spot and does not move any further. Therefore I cannot use the phone. What is the problem and how to I fix it?

And while on Safe Mode you had to remember if you had Installed any new application or change anything within your device before this problem appeared. If yes then Uninstall them and see if your device Boots up normally.